1. Field of the Invention
The present invention relates to a rotational angle detecting apparatus comprising: a plurality of detecting means, disposed to face one or a plurality of targets made of a magnetic material and provided on a rotating member, for detecting the target and outputting detection signals with mutually different phases according to the position of the target which changes with a rotation of the rotating member; operating means for operating a predetermined operation on the detection signals respectively outputted by the detecting means; and converting means for storing tables or conversion formulas, said tables representing the correlation of each operation result obtained by executing the predetermined operation by the operating means in advance with a corresponding electrical angle of the detection signals, and said conversion formulas representing the relationship between the operation result and the electrical angle of the detection signals, wherein the converting means calculates the electrical angle of the detection signals by converting the result of the operation executed by the operating means based on the table or the conversion formula, and detects the rotational angle of the rotating member based on the calculated electrical angle. And, the present invention relates to a torque detecting apparatus comprising this rotational angle detecting apparatus.
2. Description of Related Art
As a steering apparatus for automobiles, there is an electric power steering apparatus which reduces the driver's burden by assisting steering by driving an electric motor. This electric power steering apparatus comprises: an input shaft connected to a steering member (steering wheel); an output shaft connected to a drive wheel through a pinion, rack, etc.; a connection shaft connecting the input shaft and output shaft; and a torque sensor for detecting a steering torque applied to the input shaft, based on a torsional angle generated on the connection shaft, and drives and controls the steering assistant electric motor linked to the output shaft, based on the steering torque detected by the torque sensor.
The applicant of the present application in Japan proposes a rotational angle detecting apparatus comprising: a plurality of detecting means, disposed to face one or a plurality of targets made of a magnetic material provided on a rotating member, for outputting detection signals with mutually different phases according to the position of the target which changes with a rotation of the rotating member; operating means for operating a predetermined operation on the detection signals respectively outputted by the detecting means; storing means for storing the relationship between the result of the operation executed by the operating means in advance and the electrical angle of the detection signals, and means for converting the result of the operation executed by the operating means into the electrical angle of the detection signals with reference to the storing means, for detecting the rotational angle of the rotating member based on the obtained electrical angle, and also proposes a torque detecting apparatus comprising this rotational angle detecting apparatus in Japanese Patent Application Laid Open No. 2003-344188.
In the above-mentioned rotational angle detecting apparatus and torque detecting apparatus, since the relationship between the operation result and the electrical angle of the detection signals varies depending on the gap (space) between the target and a magnetic sensor (detecting means, such as an MR sensor or a hall sensor), the problem of operation errors will arise if these apparatuses cannot be mounted with the gap according to the design and if the run-out of the shaft of the target is large.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.